2277 / 2440
ENGLISH
*
*Based on 82.5% efficiency.
**When width of cut exceeds 60 feet, use a multiple of the width of cut
and increase production proportionately.
CUTTING PRODUCTION ESTIMATING
Most land clearing operations such as bulldozing,
cutting, grubbing, raking and piling are not performed
at constant speed. Because off-the-job production is
difficult to estimate for these operations, Rome Industries
has developed formulas for estimating cutting and piling
time. These formulas take into consideration variable
prime mover speeds through a factor, “B”, the base
time for each tractor to cover one hectare (2.47 acres)
of light material.
To estimate
tractor cutting time per hectare
(2.47 acres)
on a specific land clearing job, apply the factors shown
in the following table, together with data obtained from
the job survey, in the formula:
T = X [A(B)+M
1
N
1
+M
2
N
2
+M
3
N
3
+M
4
N
4
+DF]
where
T = Time per hectare (2.47 acres) in minutes
X = Hardwood or density factor affecting total time
A = Density or vine presence factor affecting base
time
B = Base time for each tractor per hectare (2.47 acres)
M = Minutes per tree in each diameter range
N = Number of trees per hectare (2.47 acres) in each
diameter range obtained from field survey
D = Sum of diameter in 30 cm (1 ft) increments of
all trees per hectare (2.47 acres) above 180 cm
(6 ft) in diameter at ground level obtained from
field survey
F = Minutes per 30 cm (1 ft) of diameter for trees
above 180 cm (6 ft) in diameter.
Hardwoods affect over-all or total time as follows:
75-100% hardwoods: Add 30% to total time (X = 1.3)
25-75% hardwoods: No change (X = 1.0)
0-25% hardwoods: Subtract 30% from total time
(X = 0.7)
Production Factors for Felling
with Rome K/G Blades
Tractor
Base
Minutes
per
hectare
(2.47
acres)
“B”
Diameter Range
Dia.
above
180 cm
per 30 cm
(6' per foot)
“F”
30-60 cm
(1-2 ft)
“M
1
”
60-90 cm
(2-3 ft)
“M
2
”
90-120 cm
(3-4 ft)
“M
3
”
120-180 cm
(4-6 ft)
“M
4
”
165 hp 85
0.7
3.4
6.8
— —
230 hp 58
0.5
1.7
3.3
10.2
3.3
305 hp 45
0.2
1.3
2.2
6.0
1.8
405 hp 39
0.1
0.4
1.3
3.0
1.0
Explanation of columns in table:
Tractor
— Based on current model tractors (power
shift when applicable) working on reasonably level
terrain (below 10% grade) with good footing, no stones,
average mixture of soft and hard woods. Tractor is in
proper operating condition, blade is sharp, and properly
adjusted.
Base Minutes
— The base figures represent the
number of minutes required for each tractor to cover a
hectare (2.47 acres) of light material where no trees
require splitting or other individual treatment. Time
required is affected by the density of material less than
30 cm (1 ft) in diameter and the presence of vines.
a. dense — 1480 trees/hectare (600 or more trees/
acre): Add 100% to base time (A = 2.0)
b. medium — 990-1480 trees/hectare (400-600 trees/
acre): No change (A = 1.0)
c. light — less than 990 trees/hectare (400 trees/
acre): Subtract 30% from total time (A = 0.7)
27-6 Edition 47
Production Estimating
●
Cutting
Land Clearing
Minutes
to travel
88 ft
Speed
mph
Production*
acres/hour
Width of Cut**
feet